The invention relates to a rack of a double-layer cleaning machine. The rack comprises a body and a walking staircase, wherein the body comprises a bottom plate, four universal wheels, handrails and a supporting rod; the four universal wheels are symmetrically arranged on the lower end face of the bottom plate; the handrails are bent L-shaped; the lower ends of the handrails are fixedly connected with the upper end face of the bottom plate; the supporting rod is connected between the handrails; the walking staircase is connected with the upper end face of the body through bolts and comprises two supporting plates, a first step plate, a second step plate, a third step plate and a fourth step plate; side faces of the supporting plates are provided with mounting lugs; the mounting lugs on the two supporting plates are symmetrically arranged on the two sides of the body through bolts; the assembly, the disassembly and the cleaning are facilitated by using a bolt connection mode; the first step plate, the second step plate, the third step plate and the fourth step plate are arranged between the two supporting plates from top to bottom in sequence. The rack can assist the existing tire cleaning machine to realize an automatic cleaning function, and has the advantages of simple structure, easiness and convenience in operation and the like.